add stdio to fcntl includes for constants

src/header/fcntl/cbindgen.toml

@@ -10,8 +10,9 @@
 # This approach was chosen because unistd.h requires parts of fcntl.h but not the other way around.
 #
 # stdarg.h brings in va_list for ...
+# stdio.h brings in SEEK_SET, SEEK_CUR, and SEEK_END
 # sys/stat.h brings in mode_t, off_t and file mode constants
-sys_includes = ["stdarg.h", "sys/stat.h"]
+sys_includes = ["stdarg.h", "stdio.h", "sys/stat.h"]
 include_guard = "_RELIBC_FCNTL_H"
 after_includes = """
 #include <bits/pid-t.h> // for pid_t from sys/types.h

src/header/fcntl/mod.rs

@@ -112,6 +112,7 @@ pub unsafe extern "C" fn openat(
     Sys::openat(fd, path, oflag, mode).or_minus_one_errno()
 }
 
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/posix_fallocate.html>.
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn posix_fallocate(fd: c_int, offset: off_t, length: off_t) -> c_int {
     // Length can't be zero and offset must be positive.